A year without summer for California, or a harbinger of a climate shift?

Mark Twain once remarked “The coldest winter I ever spent was a summer in San Francisco.” If residents and visitors along the California coast think the summer of 1999 was even cooler than usual, they are right. Several air temperature records were set (R. Renard, pers. comm., 2000). October 1999 marked a 13-month run of below-normal temperatures at Monterey, and the March–July mean was 1.4°C below the long-term average.